1. Field of the Invention
The present invention relates to an electronic device. More particularly, the present invention relates to a sliding type electronic device.
2. Description of the Related Art
Recently, portable electronic devices having a wireless communication function, like cellular phone devices are widely used. There are various types of portable electronic devices: a so-called straight type; a foldable type; and a sliding type. A foldable type portable electronic device has a display-unit casing provided with a display screen and an operation-unit casing provided with plural keys, both casings hinged together. A sliding portable electronic device has a display-unit casing and an operation-unit casing, both casings coupled together via a sliding mechanism, as disclosed in, for example, Unexamined Japanese Patent Application KOKAI Publication No. 2006-178924. As the display-unit casing slides, keys of the operation-unit casing appear or are hidden. A straight type portable electronic device has one casing, as disclosed in, for example, Unexamined Japanese Patent Application KOKAI Publication No. 2002-318640.
A portable electronic device further has a pointing device for moving a cursor, a pointer, or the like displayed on the display unit of the portable electronic device. A possible pointing device is a so-called touch pad, a joystick, a cross key, or a track ball. The straight type portable electronic device disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2002-318640 has a touch pad provided on the rear face of the casing.
Regarding the sliding type portable electronic devices, the area of the front face of the operation-unit casing is limited. Accordingly, it is difficult to provide a pointing device on the front face of the operation-unit casing, in addition to plural keys.
Further, regarding the straight type portable electronic devices, the touch pad is exposed when it is not in use and is not protected in this state.